Recently, accompanying the increase in chip size of DRAM, MPU etc., there has also been a tendency to increase the diameter of a silicon substrate used as a substrate for these devices. In the field of semiconductor manufacture, etching of an oxide film or polysilicon etc. is one of the most important steps, but with a normal parallel RIE device that was used formerly it was not possible to achieve plasma performance (for example, process pressure of less than 50 mTorr, ion saturation current of at least 1 mA/cm2 (electron density of at least 1×1010 cm−3)) required for fine pattern processing at less than 1.0 μm. In order to solve this problem, a plasma source introduced into a magnetic field was developed, and as one example of a device containing this plasma source, a magnetron plasma etching device using a dipole ring magnet (hereinafter referred to as DRM) is well known (Japanese patent laid-open No. Hei 6-37054, FIG. 24 and FIG. 25),
However, with a magnetron plasma etching device using the above described DRM generation of low pressure high density plasma is possible, but it is very difficult to control plasma generated on the base with high precision. That is, by introducing a horizontal magnetic field onto the base, it is to be expected that making the plasma density uniform and making the self bias potential uniform on the base will be difficult. At the present time, a scheme for causing the magnetic field to have a slope (Japanese Patent Laid-open No. Sho. 62-21062) and causing the magnetic field introduced into a processing space to be rotated (Japanese Patent Laid-open No, 61-208223) have been adopted as methods of making the plasma density and self bias potential uniform. However, in the method of Japanese Patent Laid-open No. Sho. 62-2 1062, there was the problem that when the process pressure etc. varied, the optimal magnetic slope also varied. On the other hand, in the method of Japanese Patent Laid-open No, 61-208223, it was anticipated from outward appearances that plasma density would be made uniform for a base in a processing space, but a mechanism for causing rotation of the magnetic field was essential, and it was difficult to miniaturize the device.
The object of the present invention is to provide a plasma etching device capable of etching with respect to a base uniformly, and without charge up damage (generated as a result of potential deviation), independently of pressure and without causing rotation of magnetic field applying means, by making the density of plasma generated on a surface of the base uniform, and making a self bias potential uniform.